Newbie question.

Hi all,
I'm an absolutely matplotlib newbie, so I'm sorry if my question is trivial. Anyway I've read the user guide and looked at the examples without finding out a solution.

Here it is my problem. Suppose I have a 2-dimensional array containg my data, and I want to produce a surface or a contour plot with it. Now the imshow() function seems the right way to go through. So far so good. Now suppose I want to draw the x,y axes for this plot, and suppose my axes are represented by **not-uniform** 1-dimensional array x[i], y[j]. How can I get the right ticks on the plot axes??

I hope to have been clear. Thanks in advance,